1. Technical Field
The present invention relates to a transport device and a transport method. More specifically, the present invention relates to a transport device and transport method which transport a long medium wound in a roll form on a shaft member so as to feed the medium while rotating the shaft member. The present invention also relates to a recording apparatus incorporating the transport device.
2. Related Art
One example of a recording apparatus which performs recording on a long medium (as one example, a long sheet) wound in a roll form on a shaft member is described in Japanese Patent Doc. JP-A-8-91658. In that apparatus, the terminus of a sheet that is used in the recording apparatus is fixed to the shaft member.
A transport device for transporting the sheet in a predetermined transport direction in the recording apparatus includes a sending roller disposed further downstream in the transport direction than a housing section where the sheet wound in a roll form is housed, and a driving motor which imparts a driving force to the sending roller. Further, a detection sensor for detecting movement of the shaft member with the sheet wound thereon is provided in the housing section.
When transporting the sheet, rotation of the sending roller is transmitted to the shaft member through the sheet, so that the shaft member rotates in a predetermined rotational direction in conjunction with the rotation of the sending roller. Then, the sheet is sent little by little from the housing section and as a result, causing the sheet to be transported to a recording area on the downstream side in the transport direction. At this time, if the sheet wound on the shaft member is almost exhausted, the shaft member, to which the terminus of the sheet is fixed, moves so as to be dragged to the transport direction side of the sheet by a driving force based on the rotation of the sending roller, which is transmitted thereto through the sheet. When such movement of the shaft member is detected by the detection sensor, it is determined that the sheet has run out, and the prescribed processing of stopping driving of the driving motor is then performed.
Incidentally, moving the shaft member so as to drag it in accordance with the sheet running-out causes a great load to act on various members such as the sending roller which is used for transporting the sheet. The driving motor that is a driving source of the sending roller. If a great load is imparted to various members in this manner, the degree of abrasion of the members becomes high, such that there is a concern that a frequency of execution of maintenance or a frequency of replacement of a component may become high. Further, a method of detecting that the roll is nearly empty is found in JP-A-8-91658, which describes a method which can be adopted in a case where the terminus of the sheet is fixed to the shaft member, but which cannot be adopted in a case where the terminus of the sheet is not fixed to the shaft member.